Reaction of trimethylaluminium, dimethyllithium cuprate and lithium tetramethylaluminate with the homochiral epoxide 8 has been studied. Intermolecular epoxide ring-opening was observed with dimethyllithium cuprate and lithium tetramethylaluminate, but acetal ring-opening followed by intramolecular epoxide ring-opening was observed with trimethylaluminium.
rapamycin - epoxide-opening - substituted tetrahydrofuran - trimethylaluminium - lithium tetramethylaluminate